The man who gunned down his ex-girlfriend in London's Harvey Nichols store, had taken cocaine, an inquest has heard.
Pech stalked Ms Bernal after she ended the relationship
Recording a verdict of suicide, Dr Paul Knapman told Westminster Coroner's Court that Michal Pech, 30, had taken a "significant" amount of the drug.
Clare Bernal, 22, was working at a perfume counter on 13 September when she was shot in front of customers.
Pech, who previously threatened to kill her, then turned the gun on himself.
Pathologist Dr Vesna Djurovic told the court: "It is difficult to determine how recently cocaine was taken and to what degree he would have been influenced by it."
Dr Knapman said the drug can cause "mental excitement" and 0.25 milligrams of cocaine per litre of blood was a "significant" amount.
"It is not fatal by any means and I have no doubt that it had some effect. The evidence overwhelmingly shows... there is a lot to indicate premeditation on behalf of Michal Pech."
He said Pech, a former Harvey Nichols security guard, died from a single gunshot wound to the head.
Witness Victoria Daniels, who was working on a cosmetics counter near Ms Bernal, told the court she saw Pech creep up on Ms Bernal.
At first, she thought he was just a "silly customer", but when he pulled out a gun, she thought he was a terrorist and started warning others to run as she fled the store.
Prosecuted for desertion
The inquest heard more of Pech's background, a dual national who was born in the Czech Republic but grew up in Slovakia.
He studied in Slovakia between 1993 and 1998, when he was prosecuted for desertion.
In 2003, after a spell working as a security guard at the United States Embassy in Bratislava, Pech arrived in the UK.
Last September, he took a job at Knightsbridge's Harvey Nichols where he met Ms Bernal and had a brief relationship with her.
But when the relationship ended, Pech, who was living in Tottenham, north London, refused to accept it and started to make pestering phone calls.
Threats to kill
He also returned to Slovakia where he bought and registered a handgun.
Pech, who had threatened to kill Ms Bernal in March, had been on bail on condition he did not contact her or go to Dulwich Village, south-east London, where she lived. She was originally from Tunbridge Wells in Kent.
He had been due to be sentenced in court on 21 September after pleading guilty to harassment.
Eight days before that though, he walked into Harvey Nichols, and shot Ms Bernal several times in the head, before killing himself.
The inquest into the death of Ms Bernal continues.